#define _CRT_SECURE_NO_WARNINGS 1
#include <ctype.h>
#include <stdio.h>

int main() {
    int ch = 0;
    while ((ch = getchar()) != EOF)
    {
        if (isalpha(ch))
        {
            printf("YES\n");
        }
        else
        {
            printf("NO\n");
        }
        getchar();
    }
    return 0;
}